VIDEO : Exclusive Interview: Christopher Nolan reveals why he cast Harry Styles for 'Dunkirk'

Christopher Nolan's new World War II drama 'Dunkirk' stars several rising young stars, such as Fionn Whitehead, Barry Keoghan, Jack Lowden and Tom Glynn-Carney. But there's also an actor making his feature film debut, despite already being one of the most famous faces on the planet: former One Direction-er Harry Styles. In this exclusive interview, Nolan tells us why he selected the singer for the movie.